Man I really don't want to read all those comments to get caught up xD.
There could be an alien race that unites a bunch of other alien races against the Empire of Gaia and wages war on Gaian outposts and bases around the galaxy. Soon entire systems and even Gaian ship captains are defecting to the enemy side, seeing that the result is inevitable. Slowly but surely, their combined forces close in on the space around Gaia, and eventually the last of the major Gaian warships protecting Gaia is destroyed.
Gaia is under attack. Because it's in the future, there are not nearly as many humans on Gaia than there were in the past. As a result, the alien forces (who could call themselves the Haides) nearly wipe out every human on Gaia. The few that are left are taken into captivity.
Suddenly, the entire Gaian Empire has been wiped out, with just small pockets of resistance and few major Gaian bases or outposts left in the galaxy. The remaining humans, scattered throughout space, now must unite to defeat what is now known as the Haiden Empire.
This is just some of what I thought of, feel free to finish the story! :)
